Stabilized surgical adhesive

ABSTRACT

Adhesive mass for surgical tape including a rubbery elastomer, zinc resinate, a filler or reinforcing agent and preferably a neutral resin.

United States Patent Johnston 51 Feb. 13, 1973 [54] STABILIZED SURGICAL ADHESIVE 2,692,245 10/1954 Groves et al ..260/27 BB 2,880,184 3/1959 G t 1. ..260/3 [75] Inventor Mlchlgan 2,559,990 7/1951 0:12:32: ..260/27 BB 73 Assigneez Schou, Inc. Chicago n 2,459,891 H1949 Nelson et al ..260/27 BB 2,964,422 12/1960 Bergstedt et a1 ..1 17/122 PA [22] Filed: Oct. 19, 1970 Prima ExaminerJohn C. Bleut e 21 A LN 82110 g 1 pp 0 Attorney-Hill, Sherman, Meroni, Gross & Simpson [52] US. Cl ..260/3, 117/122 PA, 260/4 R,

260/17.4 BB, 260/17.4 ST, 260/27 BB, [57] ABSTRACT 260/4l'5 sS Adhesive mass for surgical tape including a rubbery I 51] Int Cl Cosd 9 9/18 elastomer, zinc resinate, a filler or reinforcing agent 581 Field 01' Search ..260/3, 27 BB, 4 R, 17.4 BB, and

260/17.4 ST; 117/122 PA [56] References Cited 4 Claims, No Drawings STABILIZED SURGICAL ADHESIVE BACKGROUND OF THE INVENTION 2. Field of the Invention This invention is in the field of adhesive masses for surgical tapes, the masses including controlled amounts of zinc resinate for the purpose of accurately controlling the adhesion and tack characteristics of the product, instead of relying upon the production of zinc resinate in uncontrolled amounts as exists in current manufacturing practice.

2. Description of the Prior Art In the manufacture of adhesive masses for surgical adhesive tapes, the most widely used components are an elastomer such as natural rubber, in combination with one or more tackifying resins and a filler such as zinc oxide. Other components may be added for modification of various characteristics but in the main, the three ingredients mentioned above are basic to any commercial rubber based surgical adhesive.

The tackifying resins commonly employed in such masses are slightly acidic. In manufacturing the adhesive, a reaction takes place between the acidic resin and the zinc oxide present, forming a material known as zinc resinate. Although the tackifying resins are basically esters of abietic acid, in most cases these resins are far from pure, containing twenty or more miscellaneous components. Because of this characteristic, it is impossible to clearly define the exact nature of the zinc salts formed. Whatever the nature of the salts, however, their formation firms up the adhesive" to give it an entirely new viscoelastic characteristic. If the tackifying resin used were neutral, the adhesive would be too soft and would result in stringing and possibly adhesive transfer due to this stringy nature. This characteristic becomes even more critical when using the newer synthetic polymerssuch as the synthetic polyisoprenes which are much softer than natural rubber and tend to make a muchmore stringy adhesive.

The disadvantage arising from the present manufacturing process is that the formation of zinc resinate is uncontrollable. Studies made some time ago indicate that the amount of zinc resinate formed is very much dependent on time and temperature. As manufacturing techniques unavoidably vary somewhat in both temperature and time, the amount of zinc resinate formation is also variable with the result that the desired adhesion and tack characteristics cannot always be achieved with precision.

SUMMARY OF THE INVENTION The adhesive mass of the present invention contains controlled amounts of zinc resinate, preferably in combination with a neutral resin. The elastomer in the composition may be either natural rubber or one of the synthetic isoprene polymers or copolymers. The rubbery elastomer is included in an amount of from 25 to 35 percent by weight, the zinc resinate in an amount of from 3 to 40 percent, a filler or reinforcing agent is added in an amount of from 10 to 35 percent, and the neutral resin is added in an amount up to 37 percent by weight. The filler or reinforcing agent may be zinc oxide, but since there are no acid acting resinous components in the composition, no additional amounts of zinc resinate are formed.

Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The adhesive mass of the present invention contains from 25 to 35 percent of a rubbery elastomer or blend of elastomers. This material may be natural rubber of the pale crepe or smoked sheet variety or it may be one or more of the synthetic polyisoprenes or polyisoprene copolymers, of the type available commercially under the following trade names:

Polyisoprenes Shell Isoprene 309 Goodyear Natsyn 405 Goodyear Natsyn 400 Goodyear Natsyn 200 Goodrich Ameripol SN 600 Polyisoprene-polystyrene block copolymers Shell 1 107 Particularly good results are obtained when the elastomer is a blend containing from 10-90 percent natural rubber and -10 percent of a synthetic elastomer of the types described above.

The zinc resinate used is preferably one which has a melting point, by the ring and ball method, not in excess of about 120 C., and preferably from 80 to C., so that it can be used directly in the formulation. Zinc resinates with higher melting points can be used, however, by melting them or by dissolving them in a suitable solvent. The following list sets forth some of the commercially available zinc resinates which can be used for the purposes of the present invention:

Melting point (ring and ball) Zinc resinate Tenneco Zinc The zinc resinate is present broadly in an amount of from 3 to 40 percent by weight of the mixture, and more preferably in an amount of from 3 to 20 percent by weight. The neutral resin employed in the present invention is preferably of the hydrocarbon type, in amounts up to 37 percent by weight, and preferably from 12 to 20 percent by weight. Hydrocarbon resins suitable for this purpose are readily available from petroleum chemicals and coal tar. Suitable resins include polyindenes, coumarone-indenes, terpenes and their derivatives, polybutenes, polyisobutylenes and other thermoplastic hydrocarbon resins.

The composition may also include a filler or reinforcing agent such as titanium dioxide, zinc oxide, hydrated silica, aluminum silicate, or aluminum hydrate in amounts ranging from 10 to 35 percent by weight.

Since the composition contains no acid acting resins, the introduction of zinc oxide as a reinforcing agent does not introduce additional amounts of zinc resinate into the composition during processing.

Starch can also be added in amounts of from to 15 percent by weight and preferably from 5 to percent by weight. Plasticizers and modifiers such as mineral oil, hydrogenated polybutene having a molecular weight of about 3,000 to 20,000, lanolin, beeswax, and other conventional plasticizers and modifiers can be added in amounts fromO to l5 percent, and preferably from 3 to 7 percent.

Any adhesive mass of this type usually contains an antioxidant, in amounts up to 2 percent by weight, with the preferred percentage being from 0.1 to 2.0 percent. A typical antioxidant for use in this connection is Agerite Gel which consists of ditolylamines in combination with a petroleum wax. However, other antioxidants commonly employed in adhesive masses can also be used in the new composition.

Through the introduction of controlled amounts of zinc resinate, the adhesive formulations of the present invention are not dependent on process variables to achieve a predetermined balance between adhesion and tack.

The following examples are given to illustrate the formulations based upon different rubbery elastomers and mixtures thereof.

EXAMPLE 1 The following formulation is based upon 100 percent natural rubber.

polyvis SH Polyisobutylene 9 Hercules RT4023 Zinc Resinate 60 Goodyear RWC 38 l4 Neutral Hydrocarbon Resin 60 Agerite Gel Antioxidant l EXAMPLE 3 The following formulation is based upon a blend of synthetic elastomers.

lbs. Ameripol SN600 Polyisoprene 72 Shell 1 l07 lsoprene-Styrene block copolymer 28 Zinc Oxide 84 Starch 2l Lanolin 4.5 Polyvis 30SH Polyisobutylene 9 Neville NevChem I00 Neutral hydrocarbon Resin 45 Tenneeo 449-167 Zinc Resinate 60 0.25

The following formulation is based on a blend of natural and synthetic elastomers.

Pale Crepe Rubber 25 Shell 309 Polyisoprene 75 Zinc Oxide 84 Starch 2l Lanolin 4.5 Polyvis 30SH Polyisobutylene 9 Hercules Xl7880-4 Zinc Resinate 55 Goodyear RWC38 l4 Neutral Hydrocarbon Resin 50 Goodyear Wingstay L Antioxidant 0.25

All of the formulations of the foregoing examples gave excellent adhesion to skin and to their own backing, and are ideally suited for use as surgical adhesives. All of the formulations are showed excellent aging characteristics.

I claim as my invention:

1. An adhesive mass for surgical tapes consisting essentially of lOO parts by weight of rubbery elastomer from the group consisting of natural rubber, synthetic polyisoprenes and polyisoprene block polymers, 21 parts of starch, 4.5 parts of lanolin, 45-60 parts of neutral hydrocarbon resin, 55-60 parts of zinc resinate, 9 parts of polyisobutylene and 0.25 to 1 part of antioxidant.

2. The adhesive mass of claim 1 in which said zinc resinate has a melting point not in excess of C.

3. The adhesive mass of claim 1 in which said rubbery elastomer is natural rubber.

4. The adhesive mass of claim 1 in which'said rubbery elastomer is a synthetic polyisoprene. 

1. An adhesive mass for surgical tapes consisting essentially of 100 parts by weight of rubbery elastomer from the group consisting of natural rubber, synthetic polyisoprenes and polyisoprene block polymers, 21 parts of starch, 4.5 parts of lanolin, 45-60 parts of neutral hydrocarbon resin, 55-60 parts of zinc resinate, 9 parts of polyisobutylene and 0.25 to 1 part of antioxidant.
 2. The adhesive mass of claim 1 in which said zinc resinate has a melting point not in excess of 120* C.
 3. The adhesive mass of claim 1 in which said rubbery elastomer is natural rubber. 